Try the Italian grocery stores on Harlem Montrose area, they compete with each other so you might even get a good price. I have not bought ant porcini's in a while because I discovered that the dried mushrooms you get at Polish and eastern European grocery stores are almost as good and cheap. There is an old Butera in the Golf Mill shopping center that should have dried mushrooms and they have great double smoked bacon, polish sausage and hams. Otherwise it's a typical slightly weird ethnic grocery store.